Studies show women with a higher birthweight (a woman’s weight when she was born) have an increased risk of breast cancer, especially before menopause [55-61].
A higher birthweight doesn’t appear to be linked to higher estrogen levels in adulthood [62-64]. However, birthweight may be a marker of factors related to growth that are linked to breast cancer risk, such as adult height [63,65-66].
Other reasons behind the link between birthweight and breast cancer risk are under study.
Learn about other early life exposures and breast cancer risk.
For a summary of research studies on birthweight and breast cancer risk, visit the Breast Cancer Research Studies section.
Learn about other factors linked to the risk of breast cancer.
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